Methylenebisphosphonic acid derivatives

ABSTRACT

Novel pharmacologically active methylenebisphosphonates having formula (I) wherein R 1  -R 4  independently are C 1  -C 10  -alkyl, C 3  -C 10  -cycloalkyl, aryl, aralkyl, silyl SiR 3  or hydrogen, whereby in formula (I) at least one of the groups R 1  -R 4  is hydrogen and at least one of the groups R 1  -R 4  is different from hydrogen, Q 1  is hydrogen, hydroxyl, halogen, amino NH 2 , or OR&#39; 1 , wherein R&#39; 1  is C 1  -C 4  -alkyl or acyl, Q 2  is the group (α) wherein Y is a six-membered heterocyclic group, or a carbocyclic aromatic group, X is a bond, O, S or NR&#39;&#34;, wherein R&#39;&#34; is hydrogen, lower alkyl, or acyl, n is the integer 0 to 6, and R&#39; and R&#34; are hydrogen or lower alkyl provided that as a ring atom of the ring Y and/or a chain atom of the group X, there is always at least one heteroatom from the group O, N and S, including the steroisomers and the salts of the compounds.

The invention concerns novel methylenebisphosphonic acid derivativessubstituted at the methylene carbon, in particular novel bisphosphonicester acids and ester salts substituted at the methylene carbon, as wellas processes for the preparation of these novel compounds, andpharmaceutical formulations comprising these novel compounds.

Several publications disclose methylenebisphosphonic acids, their saltsor some tetraesters, but there are only a few disclosures ofcorresponding partial esters, tri-, di- and monoesters.

In the patents U.S. Pat. No. 4,447,256 and DE 28 31 578 (Suzuki et al.)a process is disclosed for the preparation of some pyridylaminomethylenebisphosphonic acid tetraethyl esters. According to thepatents the compounds may be used as herbicides, however, no disclosureis found of a pharmaceutical effect of the compounds.

In the patent EP 337 706 (Isomura et al.) the preparation of suchcyclyl- or heterocyclyl substituted aminomethylenebisphosphonic acidtetraesters is disclosed, wherein the ring substituent is either partlyor fully saturated.

In the patent EP 282 320 (Sakamoto et el.) the preparation of someisoxazolyl substituted aminomethylenebisphosphonic acid tetraalkylesters as well as the preparation of two partial esters is disclosed.

In the patent EP 298 553 (F. H. Ebetino) the preparation ofmethylenephosphonoalkyl phosphinates, substituted at the methylenecarbon, is disclosed.

The preparation of tetraesters of methylenebisphosphonic acids has beendescribed also in the publications: J. Am. Chem. Soc. 78, (1956) 4450;J. Chem. Soc. (1959) 2272; J. Am. Chem. Soc. 84 (1962) 1876; J. Org.Chem. 35, (1970) 3149; J. Org. Chem. 36, (1971) 3843 and Phosphorus,Sulfur and Silicon 42, (1989) 73, EP patent application 221 611.

According to the invention it has been discovered that the novelsubstituted partial esters of methylenebisphosphonic acids and theirsalts in many cases exhibit more favourable properties than thecorresponding bisphosphonic acids and salts due to their better kineticsand availability, their ability to participate as complex formers in theregulation of the metabolism of the organism being maintained.

They are well suited for the treatment of disorders relating to themetabolism of calcium and of other, especially bivalent metals. They maybe used both for the treatment of diseases in the skeletal system,especially of bone formation and resorption disorders, such as ofosteoporosis and Paget's disease, as well as for the treatment ofdiseases in the soft tissues, such as of deposition and mineralisationconditions and bone formation disorders.

On the other hand, being pyrophosphate analogs, the new substitutedmethylenebisphosphonic acid derivatives also are suitable for thetreatment of disorders in the (pyro)phosphate functions of the organism,including those functions, wherein an active, but disturbance-prone orwrongly functioning organic part is coupled to (pyro)phosphate or actsas a metal complex or a combination of the last mentioned.

The novel bisphosphonates regulate either directly or over an indirectmechanism the quality and level of cations and/or pyrophosphatecompounds freely present in the body fluids as well as of that bindingto, active in and liberated from the tissues. Thus they are able toregulate the cellular metabolism, growth and destruction. Consequentlythey are useful for the treatment of e.g. cancer of the bone andmetastases thereof, ectopic calcifications, urolithiasis, rheumatoidarthritis, bone infections and bone degradation.

Typical for the novel substituted methylenebisphosphonates is aselective desired and controlled action, providing for a bettertherapeutic index.

The invention concerns novel methylenebisphosphonic acid derivatives ofthe general formula I ##STR1## in which formula R¹, R², R³ and R⁴independently are a straight or branched optionally unsaturated C₁ -C₁₀-alkyl, optionally unsaturated C₃ -C₁₀ -cycloalkyl, aryl, aralkyl, silylSiR₃ or hydrogen, whereby in the formula I at least one of the groupsR¹, R², R³ and R⁴ is hydrogen and at least one of the groups R¹, R², R³and R⁴ is different from hydrogen,

Q¹ is hydrogen, hydroxyl, halogen, amino NH₂, or OR'₁, wherein R'₁ is C₁-C₄ -alkyl or acyl,

Q² is the group ##STR2## wherein Y is an optionally substituted,saturated, partly saturated or aromatic six-membered heterocyclic group,or a carbocyclic aromatic group, whereby the heterocyclic groups cancontain 1 to 3 heteroatoms from the group N, O and S, X is a bond, O, Sor NR'", wherein R'" is hydrogen or lower alkyl with 1 to 4 C-atoms,acyl, n is the integer 0 to 6,

and R' and R" are independently hydrogen or lower alkyl with 1 to 4C-atoms, provided that as a ring atom of the ring Y and/or a chain atomof the group X, there is always at least one heteroatom from the groupof O, N and S, including the stereoisomers, such as the geometricalisomers and the optically active isomers, of the compounds, as well asthe pharmacologically acceptable salts of the compounds.

The groups R¹, R², R³ and R⁴ are independently a straight or branchedalkyl, alkenyl or alkynyl group and they contain 1 to 10, respectively 2to 10 carbon atoms, preferably 1 to 7, respectively 2 to 7, andadvantageously 1 to 4, respectively 2 to 4 carbon atoms.

Optionally unsaturated cycloalkyl is cycloalkyl or cycloalkenyl with 3to 10 C-atoms, preferably, however, cyclopropyl, -butyl, -pentyl, or-hexyl.

Aryl or aralkyl as the groups R¹, R², R³ and R⁴ means optionally C₁ -C₄-lower alkyl, -lower alkoxy or halogen substituted monocyclic aryl oraralkyl, such as phenyl and benzyl, preferably, however, unsubstitutedphenyl or benzyl.

Halogen is fluorine, chlorine, bromine or iodine.

Acyl is alkyl-, aryl- or arylalkylcarbonyl, or alkoxy-, aryloxy- oraralkoxycarbonyl, wherein alkyl contains 1 to 4 carbon atoms, and aryland aralkyl have the same meaning as before.

In the silyl group SiR₃ the group R is lower alkyl containing 1 to 4C-atoms, and is especially methyl, ethyl, isopropyl, butyl, t-butyl, orit is phenyl or R-substituted phenyl, whereby also differentcombinations of lower alkyl and phenyl groups come into question, suchas dimethyl t-butyl, methyl diisopropyl, dimethyl phenyl, diethylphenyl, methyl t-butyl phenyl, diisopropyl-(2,6-dimethyl phenyl).

As the heteroaromatic and saturated heterocyclic group Y, respectively,nitrogen, oxygen and/or sulfur containing six-membered unsaturated ringgroups come into question, such as pyridine, pyrimidine, pyrazine,pyridazine, oxazine, thiazine, triazine, as well as correspondingsaturated groups, such as piperidine, piperazine, morpholine, oxathiane,dithiane, thiomorpholine etc. The hetercyclic groups may be substitutedas has been described for aryl and aralkyl below.

The group Y means as a carbocyclic aromatic group a substituted orunsubstituted aromatic ring, such as a monocyclic aryl or aralkyl,especially phenyl, or a conjugated or bridged unsaturated or partlysaturated ring system, such as naphtyl, phenanthryl, indenyl, indanyl,tetrahydronaphtyl, biphenyl, di- and triphenyl methyl etc.

Monocyclic aryl and aralkyl may be illustrated with the formula ##STR3##wherein the groups D' mean independently C₁ -C₄ -alkyl, -alkoxy, halogenor nitro, m' is the integer 0 to 3 and m the integer 0 or 1, and D meansa straight or branched C₁ - C₆ -alkylene, -alkenylene or -alkynylene.Halogen is chlorine, bromine, fluorine or iodine.

The group Y--X-- in the formula I contains at least one heteroatom fromthe group O, N and S as a ring atom in Y and/or as chain atom in X.

Salts of the compounds of the formula I are especially their salts withpharmaceutically acceptable bases, such as metal salts, for examplealkalimetal salts, especially lithium, sodium and potassium salts,alkaline earth metal salts, such as calcium or magnesium salts, copper,aluminium or zinc salts, as well as ammonium salts with ammonia or withprimary, secondary and tertiary, both aliphatic and alicyclic as well asaromatic amines, and quaternary ammonium salts, such as halides,sulphates and hydroxides, salts with aminoalcohols, such as ethanol-,diethanol- and triethanolamines, tris(hydroxymethyl)aminomethane, 1- and2-methyl- and 1,1-, 1,2- and 2,2-dimethylaminoethanols, N-mono- andN,N-dialkylaminoethanols, N-(hydroxymethyl- andethyl)-N,N-ethanediamines, as well as amino crown ethers and cryptates,and heterocyclic ammonium salts, such as azetidinium, pyrrolidinium,piperidinium, piperazinium, morpholinium, pyrrolium, imidazolium,pyridinium, pyrimidinium, quinolinium, etc., salts.

Good results have been obtained with the following mono- or dimethyl-,mono- or diethyl-, mono- or diisopropyl esters, wherein Q¹ is hydrogenand Y is a heterocyclic group, such as unsubstituted or methylsubstituted pyridine or piperidine, n is 0, and X is NH or S, andespecially good results have been obtained with the following compounds:

[[(6-methyl-2-pyridinyl)amino]methylidene]bisphosphonic acidP,P'-diethyl ester,

[[(2-pyridinyl)amino]methylidene]bisphosphonic acid P,P'-diethyl ester,

[[(2-pyridinyl)amino]methylidene]bisphosphonic acid P,P-methyl ester,

[[(3-methyl-2-pyridinyl)amino]methylidene]bisphosphonic acidP,P'-diethyl ester,

[[(4-methyl-2-pyridinyl)amino]methylidene]bisphosphonic acidP,P'-diethyl ester,

[[(2-pyridinyl)thio]methylidene]bisphosphonic acid monoisopropyl ester,

[[(4-chlorophenyl)thio]methylidene]bisphosphonic acid P,P'-dimethyl andmonoethyl ester,

[[(6-methyl-2-pyridinyl)amino]methylidene]bisphosphonic acid monoethylester,

[[(3-methyl-2-pyridinyl)amino]methylidene]bisphosphonic acid monomethylester,

[[1-hydroxy-2-(3-pyridinyl)]ethylidene]bisphosphonic acid monoisopropylester,

[[1-hydroxy-2-(3-pyridinyl)-]ethylidene]bisphosphonic acid monomethylester,

[2-(2-pyridinyl)ethylidene]bisphosphonic acid monoisopropyl ester,

[2-(3-pyridinyl)ethylidene]bisphosphonic acid monomethyl ester,

[[(3-pyridinyl)amino]methylidene]bisphosphonic acid P,P'-dimethyl ester,

[[(3-pyridinyl)thio]methylidene]bisphosphonic acid P,P'-diethyl ester,

[[(4-pyridinyl)thio]methylidene]bisphosphonic acid P,P'-diethyl ester,

[[(3-pyridinyl)thio]methylidene]bisphosphonic acid monoisopropyl ester.

The invention concerns also a process for the preparation of thecompounds of the formula I, according to which

a) a methylenebisphosphonic acid tetraester of the formula II ##STR4##in which formula Q¹ and Q² have the same meaning as above, and R¹, R²,R³ and R⁴ have the same meaning as above, except hydrogen, isselectively hydrolysed

to a triester corresponding to the formula I, wherein one of the groupsR¹, R², R³ and R⁴ has the meaning of hydrogen, or a salt thereof, or

to a diester corresponding to the formula I, wherein two of the groupsR¹, R², R³ and R⁴ have the meaning of hydrogen, or a salt thereof, or

to a monoester corresponding to the formula I, wherein three of thegroups R¹, R², R³ and R⁴ have the meaning of hydrogen, or a saltthereof, or

b) a bisphosphonic acid of the formula ##STR5## or a metal or ammoniumsalt of this compound, or the corresponding acid tetrachloride, whereinQ¹ and Q² have the same meaning as above, is esterified selectively byreacting the same with an esterification reagent corresponding to thedesired groups R¹, R², R³ and R⁴,

to a monoester corresponding to the formula I, wherein three of thegroups R¹, R², R³ and R⁴ have the meaning of hydrogen, or

to a diester corresponding to the formula I, wherein two of the groupsR¹, R², R³ and R⁴ have the meaning of hydrogen, or

to a triester corresponding to the formula I, wherein one of the groupsR¹, R², R³ and R⁴ has the meaning of hydrogen, or to the correspondingester salts of the said partial esters, or

c) a phosphonate having the formula ##STR6## is reacted with anactivated phosphate or a hydrogen phosphonate corresponding to theformula X ##STR7## wherein in the formulas Y is hydrogen, hydroxy orhalogen or other leaving group, Z is hydrogen, halogen, acyloxy,sulphonyloxy, alkoxy or aryloxy, and R¹, R², R³ and R⁴ and Q¹ and Q²have the same meaning as in the formula I, or Q¹ and Q² form adouble-bonded oxygen or an imino group, or is reacted with a phosphitecorresponding to the formula X, or

d) a bisphosphonate corresponding to the formula I, which instead of Q²has a carbanion site, is reacted with ω-leaving group substituted Q², ora bisphosphonate corresponding to the formula I, which instead of Q²contains a leaving group, is reacted with a ω-carbanion corresponding toQ², or a (Q² -C₁)-ω-carbanion is added by Michael addition inalkylidenebisphosphonates, or

e) a bisphosphonite compound having the formula ##STR8## wherein R¹, R²,R³ and R⁴ and Q¹ and Q² have the same meaning as in the formula I, orthe corresponding hydrogen phosphonate compound, is oxidized to acompound of the formula I, and if desired, the partial ester acidsobtained according to steps a) to e) are converted to partial estersalts, or the partial ester salts obtained are converted to the partialester acids, and/or, if desired, a compound obtained according to theformula I is converted into some other compound according to the formulaI by hydrolyzing, esterification or transesterification, and/or in acompound of the formula I, a group Q¹ is converted into another group Q¹within the scope of the definition.

According to one process the compounds are thus prepared by selectivehydrolysis of the tetraesters corresponding to the formula I. As thestarting material thus a tetraester is used, wherein the groups R¹ to R⁴and Q¹ and Q² have the same meaning as above and this tetraester ishydrolyzed stepwise to the triester III, diester IV and V and themonoester VI. If necessary, the partial ester or its salt may beisolated and purified by extraction, fractional crystallization orchromatographically, and if desired, a free acid may be converted into asalt or a salt into the free acid.

This reaction is shown in the appended Scheme 1 (the reaction takesplace in the direction of the upper arrow). ##STR9##

The hydrolysis of the tetraesters II may be carried out by treating bothwith an acid and a base, using thermal cleaving, and in certain casesalso using water, alcohols, or other neutral or non-neutraltransalkylation, -silylation and -arylation reagents. The hydrolysistakes place advantageously at a temperature range of 10° to 150 ° C. Theacids are advantageously conventional inorganic acids, such ashydrochloric acid, sulphuric acid, phosphoric acid, and Lewis acids,such as borotrifluoride etherate, titanium tetrachloride, etc., as wellas a number of organic acids, such as oxalic acid, formic acid, aceticacid and other carboxylic acids, methanesulphonic acid and othersulphonic acids, such as tosyl acid, further chlorine and fluorinesubstituted carboxylic and sulphonic acids, such as trichloroacetic acidand trifluoromethanesulphonic acid, and their aqueous solutions.

The bases are advantageously alkali and ammonium hydroxides and ammoniaand the aqueous solutions thereof, as well as a number of amines, suchas primary, secondary and tertiary amines, such as e.g. diethyl-,triethyl-, diisopropyl- and tributylamine, aniline, N- and N,N-alkylsubstituted anilines and heterocyclic amines, such as pyridine,morpholine, piperidine, piperazine etc., and hydrazines, such asN,N-dimethyl hydrazine.

In addition, acids and bases bound to a solid substrate may be used,such as Amberlites, either in the presence of an organic solvent orwater or various solvent mixtures, or in the absence thereof.

Further by treating with certain alkalimetals, such as sodium andlitium, or with suitable inorganic salts, such as with sodium iodide,litium bromide, ammonium chloride and NaBr/PTC, the ester group may beconverted to its corresponding salt, such as to the sodium, ammonium andlitium salt.

Thermal cleaving usually takes place at a temperature of about 100° to400° C., usually, however, at a temperature of not more than 250° C. Thepresence of a suitable catalyst, such as an acid or an acid solution, ora quaternary ammonium salt, makes it possible to perform the reactionfaster and at a lower temperature. Certain active substituents, such asbenzyl and allyl, may be removed by catalytic reduction orelectrolytically.

To improve solubility and to control the reaction temperature during thereactions, organic, inert solvents, such as hydrocarbons, lower alcoholsand stable ketones and esters, alkyl halides, such as chloroform,dichloromethane and -ethane, ethers, such as dioxan, dimethoxy ethane,diglyme, acetonitrile, etc., may be used as co-solvents.

When the groups R¹ to R⁴ in the tetraester according to the formula IIare the same, the hydrolysis takes place stepwise, and it is interruptedwhen the concentration of the desired partial ester is at its greatest.

In order to prepare a specific partial ester structure, it isadvantageous to use a tetraester of the formula II wherein the estergroups are not the same, but groups which are different with respect tothe hydrolysis rate. It has, for example, been discovered that thehydrolysis rate of alkyl and silyl esters is dependant on the structureas follows:

silyl>tert>sec>prim

It is possible to affect the hydrolysis rate by changing also the sizeand shape of the alkyl and silyl substituent as well as by electronicalfactors. It is often possible to perform a transesterification in orderto change the stepwise hydrolysis of the different ester sites.Especially the methyl ester may advantagenously be converted to thecorresponding acid over a silyl ester.

Pure partial esters may thus be prepared in an advantageous manner byperforming a selective hydrolysis of mixed esters of the formula I,which have been prepared using ester groups which are advantageous fromthe point of view of hydrolysis.

Also other selective hydrolysis reactions known especially fromphosphate and monophosphonate chemistry may be used.

The progress of the hydrolysis may be followed for examplechromatographically or by means of ³¹ P-NMR spectroscopy. The reactionmay be interrupted when the level of the desired partial ester is at itsgreatest and the product may be isolated from the reaction mixtureeither as the free acid or as a salt by precipitation, extraction orchromatographically, and the salt form may be converted to the free acidor the free acid to its salt.

The compounds according to this invention may be prepared also byselective esterification of bisphosphonic acids in accordance with theabove mentioned reaction Scheme 1 (the reaction takes place in thedirection of the lower arrow).

As a starting material a tetraacid according to the formula VII (R¹ toR⁴ =H) may then be used, which can be as a free acid or in the form of asalt, such as a metal or ammonium salt, or the corresponding phosphonicacid tetrachloride may be used, and depending on the desired end result,1 to 4 equivalents of the desired aliphatic or aromatic alcohol, or thecorresponding activated alkylation, silylation and arylation reagents,such as ortoesters, ketene acetals and other suitable transfer reagentsfor alkyl, silyl and aryl groups, such as diazo compounds, activecarboxylic acid esters, sulphates, etc. The reaction is usuallyperformed under anhydrous conditions, preferably in the temperaturerange of 0° to 150° C., or when using an inert co-solvent, at theboiling point thereof.

The esters II to IV may also be prepared in a nucleophilic substitutionreaction between the bisphosphonate anion, often the ammonium salt, andan organic halide or sulphonate, or in a condensation reaction between aphosphonic acid group and a suitable alcohol or a phenol using a reagentfor cleaving off water, such as carbodiimides.

Pure partial esters, also mixed esters, may thus be prepared byselective esterification, if necessary stepwise, of tetraacids of theformula VII. Also other selective esterification reactions may beapplied known primarily from phosphate and monophosphonate chemistry.

The progress of the esterification reactions may be followed, forexample, chromatographically or using ³¹ P-NMR and the reaction isinterrupted when the content of the desired partial ester is at itsgreatest and this is isolated from the reaction mixture byprecipitation, extraction or chromatographically and, if desired, a saltform obtained is converted to the free acid or the free acid isconverted to its salt.

Partial esters according to .the invention may also be prepared byconstructing the P--C--P frame from its parts ##STR10## wherein in theformula Y is hydrogen, hydroxy or halogen or other leaving group, Z ishalogen, acyloxy, sulphonyloxy, alkoxy, or aryloxy, and R¹ to R⁴ and Q¹and Q² have the meaning given above, or Q¹ and Q² are double-bondedoxygen or an imino group. As the base, for example, sodium hydride,butyl litium or litium diisopropylamide may be used. In the startingmaterial optionally present free acid sites (one of the groups R¹ to R⁴=H) have to be neutralized, by using a sufficient amount of base, priorto the coupling reaction. Also active sites in the groups Q¹ and Q² haveto be neutralized or the said active site has to be protected with aprotecting group.

Also the Michaelis-Arbuzov reaction may be used, whereby the secondreacting compound is a phosphite, or the Michaelis-Becker reaction,whereby Z is hydrogen.

In certain instances the group Q¹ may be introduced by an exchangereaction, or an oxidation or reduction reaction, for example hydroxylmay be obtained from hydrogen, halogen or amino, the amino group may beobtained from halogen or hydroxyl, and hydrogen may be obtained fromhalogen, and halogen may be obtained from hydrogen.

Q² may also be brought into the molecule either by a reaction involvinga bisphosphonate carbanion or corresponding C-halogen or other leavinggroup, whereby the Q² -reagent is ω-substituted with a leaving group, orcorrespondingly is a ω-carbanion.

The compounds according to the invention may also be prepared byapplying the Michael addition to alkylidene phosphonates described inthe EP patent application 0 221 611.

The esters according to the invention may also be prepared fromP--C--P-structures at a lower oxidation level by oxidation ##STR11##whereby in the formulas R¹ to R⁴ and Q¹ and Q² have the meaning givenabove, and whereby the phosphonite structure may exist in an equilibriumwith the hydrogenphosphonate structure. All conventional oxidationagents, or their solutions, such as hydrogen peroxide, perhalogencompounds, peracids, permanganate etc., come into question.

The partial esters of bisphosphonic acid according to the invention mayalso be prepared from other partial esters by performing an intra- orintermolecular exchange reaction.

The tetraesters II and corresponding tetraacids IV used as startingmaterials in the above reactions may be prepared by processes known assuch from literature by constructing the P--C--P frame from its parts,for example using the above mentioned Michaelis-Becker-,Michaelis-Arbuzov- or carbanion reaction, also stepwise, whereby R¹ toR⁴ may be chosen and advantageously introduced as parts of thebisphosphonate taking into account the structure of the desired partialester, and by suitably substituting this frame or an anion obtainedtherefrom, for example by an alkylation or an addition reaction.

N-substituted (aminomethylidene)bisphosphonic acid tetraesters may beprepared by reacting an amino substituted compound with alkylortoformiate and reacting the imino ether derivative obtained as anintermediate with dialkyl phosphite either as such or in purified form.

N-substituted (aminoalkylidene)bisphosphonic acid esters may also beprepared for example in a reaction between alkenyl bisphosphonic acidesters and amino derivates, or by substituting suitably(alkylidene)bisphosphonic acid esters.

O-substituted (oxyalkylidene)bisphosphonic acid tetraesters may beprepared for example by reacting suitable dichloroalkyl ethers withtrialkyl phosphites and by reacting the thus obtained dialkyl(chloroalkoxymethyl)phosphonates with sodium dialkyl phosphite.

(Thiomethylidene)bisphosphonates may suitably be prepared by reacting adisulfide and a methylenebisphosphonate anion.

Taking into account the preparation of a desired partial ester, theprepared tetraesters may, if necessary, be converted to other suitabletetraesters using exchange reactions. Thereby the groups OR¹ to OR⁴ maybe exchanged directly or over the corresponding phosphonochloride or byapplying other known processes.

Optically active partial esters may be best prepared by using knownoptically active compounds, such as optically active alcohols, in thepreparation of the above mentioned starting materials, intermediates andend products, or in the exchange reactions.

The properties of the compounds according to the invention have beentested in the following test systems.

The parathyroid hormone stimulated bone resorption inhibition activityof the compounds in vitro in mouse calvaria, as well as the inhibitionof retinoid induced bone resorption in thyroparathyroidectomised rats invivo were determined (Reynolds & Dingle (Calc Tiss Res 1970; 4:339, andTrechsel et al. (J Clin Invest 1987; 80:1679)).

                  TABLE 2                                                         ______________________________________                                        Antiresorptive activity                                                       Inhibition of resorption (%)                                                                            150                                                                     100 μm                                                                           μmole/kg                                                             in vitro                                                                            in vivo                                             ______________________________________                                        Clodronate            43      64                                              [[(3-methyl 2-pyridinyl)amino]                                                                      51      ND                                              methylidene]bisphosphonate                                                    [[(2-pyridinyl)amino]-                                                                              56      >100                                            methylidene]bisphosphonate                                                    P,P'-diethyl [[(3-methyl 2-                                                                         43      66                                              pyridinyl)amino]-                                                             methylidene]bisphosphonate                                                    P,P'-diethyl [[(2-pyridinyl)amino]-                                                                 33      65                                              methylidene]bisphosphonate                                                    monoisopropyl [[(2-pyridinyl)thio]-                                                                 50      87                                              methylidene]bisphosphonate                                                    ______________________________________                                         ND = Not determined.                                                     

From the table the superiority of the compounds of the invention,especially their better relative in vivo-anti-resorptive activity isapparent when taking into account that they do not bind to hydroxyapatite, even though they inhibit crystal growth. They provide for abetter therapeutic index, exhibiting lesser side effects.

The partial esters of substituted bisphosphonic acids of the formula Imay be used as pharmaceuticals as such, or as their pharmacologicallysuitable salts, such as the alkali or ammonium salts. Such salts may beprepared by reacting the ester acids with the corresponding inorganic ororganic bases. Depending on the reaction conditions, the ester salts maybe formed also directly in the above mentioned reactions.

The new compounds I according to this invention may be administeredenterally or parenterally. All conventional administration forms, suchas tablets, capsules, granules, syrups, solutions, implants andsuspensions come into question. Also all adjuvants for manufacture,dissolution and administration of the preparation, as well asstabilizers, viscosity regulating and dispersion agents and buffers, maybe used.

Such adjuvants include i.a. tartrate and citrate buffers, alcohols, EDTAand other nontoxic complexing agents, solid and liquid polymers andother sterile substrates, starch, lactose, mannite, methylcellulose,talc, silicic acids, fatty acids, gelatine, agar-agar, calciumphosphate, magnesium stearate, animal and vegetable fats and, ifdesired, flavouring and sweetening agents. The dosage depends on severalfactors, for example on the manner of administration, species, age andindividual condition. The daily doses are about 0.1 to 1000 mg, usually1 to 100 mg per person, and they may be adminstered as a single dose ormay be divided into several doses. In the following, examples of atypical capsule and a tablet are given:

    ______________________________________                                                       mg/caps.                                                       ______________________________________                                        Capsule                                                                       Active ingredient                                                                              10.0 mg                                                      Starch           20.0 mg                                                      Magnesium stearate                                                                              1.0 mg                                                      Tablet                                                                        Active ingredient                                                                              40.0 mg                                                      Microcrystalline 20.0 mg                                                      cellulose                                                                     Lactose          67.0 mg                                                      Starch           10.0 mg                                                      Talc              4.0 mg                                                      Magnesium stearate                                                                              1.0 mg                                                      ______________________________________                                    

For medicinal use, also an intramuscularly or parenterally administeredpreparation may be made, for example an infusion concentrate, wherein asadjuvants e.g. sterile water, phosphate buffer, NaCl, NaOH or HCl orother known pharmaceutical adjuvants suitable for the purpose may beused.

The compounds in ester-acid form according to the invention are liquidsor waxy substances, usually soluble in organic solvents and in someinstances in water. The ester salts are solid, crystalline or typicallypowdery substances which usually dissolve well in water, in someinstances in organic solvents, but only certain structure types beingpoorly soluble in all solvents. The compounds are very stable, also intheir neutral solutions at room temperature.

The structure of the compounds may easily be verified with ¹ H-, ¹³ C-and ³¹ P-NMR-spectroscopy and FAB-masspectrometry, or when silylated,with EI-masspectrometry. For concentration and impurity determinations31P-NMR-spectroscopy is very suitable (85% H₃ PO₄ δ=0). Also for polarcompounds as such ion exchange and exclusion-HPLC may be used and fortetraesters and silylated ester acid derivatives GLC or GC/MS may beused. From the compounds sodium and other metals were determinedseparately as well as the possible crystal water content. From the aminesalts, nitrogen was determined.

The following examples illustrate the invention without limiting thesame in any way.

PREPARATION OF STARTING MATERIALS Example A Preparation of[[(3-Methyl-2-pyridinyl)amino]methylidene]bisphosphonic Acid TetraethylEster

A mixture of 2-amino-3-methylpyridine (0.2 moles), triethyl ortoformiate(0.24 moles) and diethylphosphite (0.42 moles) was heated at 150° C. for30 minutes, whereafter the ethanol formed in the reaction was distilledoff. The mixture was cooled and the raw product was purifiedchromatographically (eluent methanol-dichloromethane, 1:1). Yield 37 g(49%; 31-P NMR 18.86 ppm; CDCl₃).

In the same manner may be prepared:

[[(4-Methyl-2-pyridinyl)amino]methylidene]bisphosphonic acid tetraethylester from 2-amino-4-methylpyridine (31-P NMR 18.60 ppm; CDCl₃).

[[(6-Methyl-2-pyridinyl)amino]methylidene]bisphosphonic acid tetraethylester from 2-amino-6-methylpyridine (31-P NMR 18.75 ppm; CDCl₃).

[[(2-Pyridinyl)amino]methylidene]bisphosphonic acid tetraethyl esterfrom 2-aminopyridine (31-P NMR 18.62 ppm; CDCl₃).

[[(3-Pyridinyl)amino]methylidene]bisphosphonic acid tetraethyl esterfrom 3-aminopyridine.

[[(3-Pyridinyl)amino]methylidene]bisphosphonic acid tetraisopropyl esterfrom 3-aminopyridine.

[[(2-Pyridinyl)amino]methylidene]bisphosphonic acid tetramethyl esterfrom 2-aminopyridine (31-P NMR 16.00 ppm; CDCl₃).

[[(4-Pyridinyl)amino]methylidene]bisphosphonic acid tetraethyl esterfrom 4-aminopyridine.

[[(3-Hydroxy-2-pyridinyl)amino]methylidene]bisphosphonic acid tetraethylester (31-P NMR 18.76 ppm; CDCl₃).

[[(4-Methoxy-3-pyridinyl)amino]methylidene]bisphosphonic acid tetraethylester (31-P NMR 18.15 ppm; CDCl₃).

[[(4,6-Dihydroxy-2-pyrimidyl)amino]methylidene]bisphosphonic acidtetraethyl ester.

Example B Preparation of[1-Hydroxy-2-(2-pyridinyl)ethylidene]bisphosphonic Acid TetramethylEster

To a chloroform solution of trimethylphosphite (0.1 moles) and dimethylphosphite (0.1 moles) (2-pyridinyl) acetyl chloride (0.1 moles)dissolved in chloroform was slowly added at 0° C. The mixture was heatedat 80° C. for 10 hours. The solvent was evaporated at reduced pressure,and the product purified with flash chromatography (eluent methylenechloride-methanol 1:1). Yield 14 g (41%).

In the same manner may be prepared:

[1-Hydroxy-2-(3-pyridinyl)ethylidene]bisphosphonic acid tetraisopropylester (31-P NMR 20.02 ppm; CDCl₃).

[1-Hydroxy-2-(4-pyridinyl)ethylidene]bisphosphonic acid tetraisopropylester.

Example C Preparation of [2-(2-Pyridinyl)ethylidene]bisphosphonic AcidTetraisopropyl Ester

Sodium hydride (0.15 moles) was slurried in a nitrogen atmosphere intodry toluene and tetraisopropyl methylenephosphonate (0.065 moles) wasadded slowly. The solution was stirred until the generation of hydrogenhad ceased. 2-picolyl chloride (0.72 moles) dissolved indimethylformamide was added slowly and the solution refluxed for 12hours. The solvents were evaporated and the product purified with flashchromatography (eluent toluene-acetone, 1:1). Yield 58%,

In the same manner may be prepared:

[[(2-Pyridinyl)thio]methylidene]bisphosphonic acid tetramethyl esterfrom 2,2'-dipyridinyl disulphide (31 P-NMR 23.26 ppm; CDCl₃).

[[(2-Pyridinyl)thio]methylidene]bisphosphonic acid tetraisopropyl esterfrom 2,2'-dipyridinyl disulphide (31-P NMR 18.85 ppm; CDCl₃).

[2-(3-pyridinyl)ethylidene]bisphosphonic acid tetraisopropyl ester (31-PNMR 20.13 ppm; CDCl₃).

[2-(3-pyridinyl) ethylidene]bisphosphonic acid tetraethyl ester (31-PNMR 22.00 ppm; CDCl₃).

[[(3-Pyridinyl)thio]methylidene]bisphosphonic acid tetraisopropyl esterfrom 3,3'-dipyridinyl disulphide.

[[(4-Pyridinyl)thio]methylidene]bisphosphonic acid tetraethyl ester from4,4'-dipyridinyl disulphide.

[[(2-Pyridinyl)thio]methylidene]bisphosphonic acid tetraethyl ester from2,2'-dipyridinyl disulphide

[[(2-Pyridinyl)thio]methylidene]bisphosphonic acid isopropyl trimethylester from 2,2'-dipyridinyl disulphide and isopropyl trimethylmethylenebisphosphonate (31-P NMR 20.21/17.5 ppm; CDCl₃).

[[(4-Chlorophenyl)thio]methylidene]bisphosphonic acid tetraisopropylester from bis(4-chlorophenyl) disulphide (31-P NMR 18.14 ppm; CDCl₃).

[[(4-Chlorophenyl)thio]methylidene]bisphosphonic acid tetraethyl esterfrom bis(4-chlorophenyl) disulphide

[2-(2-Pyridinyl)ethylidene)bisphosphonic acid P,P-dimethylP',P'-diisopropyl ester from 2-picolyl chloride and P,P-dimethylP',P'-diisopropyl methylenebisphosphonate.

[2-(3-Pyridinyl)ethylidene]bisphosphonic acid P,P'-dimethylP,P'-diisopropyl ester from 3-picolyl chloride ja P,P'-dimethylP,P'-diisopropyl methylenebisphosphonate.

[2-(4-Pyridinyl)ethylidene]bisphosphonic acid tetraethyl ester from4-picolyl chloride.

Further, by using as a base litium diisopropylamide, one may prepare

[[(4-Chlorophenyl)thio)methylidene)bisphosphonic acid P,P'-dimethylP,P'-bis(trimethylsilyl) ester.

[2-(2-Pyridinyl)ethylidene]bisphosphonic acid P-ethylP,P',P'-tris(trimethylsilyl) ester.

[2-(3-Pyridinyl)ethylidene]bisphosphonic acid P-methylP,P',P'-tris(trimethylsilyl) ester

[[(4-Chlorophenyl)thio)methylidene)bisphosphonic acid P-ethylP,P',P'-tris(trimethylsilyl) ester.

Example 1 Preparation of[[(6-Methyl-2-pyridinyl)amino]methylidene]bisphosphonic Acid P,P-diethylEster

Into an acetonitrile solution of[[(6-methyl-2-pyridinyl)amino]methylidene]bisphosphonic acid tetraethylester (0.02 moles) and sodium iodide (0.04 moles) chlorotrimethylsilane(0.042 moles) was slowly added at room temperature. The solution wasstirred for 3 hours, whereafter the solvent was evaporated at reducedpressure. The evaporation residue was dissolved in a small amount ofwarm water, and the solution was made alkaline with a dilute sodiumhydroxide solution. The product was precipiated by adding ethanol (31-PNMR 11.34/22.79 ppm, J=34.3; D₂ O).

In a corresponding manner the following esters and their sodium saltsmay be prepared:

[[(2-Pyridinyl)thio]methylidene]bisphosphonic acid P,P-diisopropyl esterfrom the corresponding tetraisopropyl ester (31-P NMR 9.34/20.44 ppm;J=14.9 Hz; D₂).

[[(2-Pyridinyl)thio]methylidene]bisphosphonic acid P,P-diethyl esterfrom the corresponding tetraethyl ester.

[[(3-Pyridinyl)thio]methylidene]bisphosphonic acid P,P-diisopropyl esterfrom the corresponding tetraisopropyl ester.

[[(4-Pyridinyl)thio]methylidene]bisphosphonic acid P,P-diethyl esterfrom the corresponding tetraethyl ester.

[2-(2-Pyridinyl)ethylidene]bisphosphonic acid P',P'-diisopropyl esterfrom the corresponding P,P-dimethyl P',P'-diisopropyl ester.

[2-(3-Pyridinyl)-1-hydroxyethylidene]bisphosphonic acid P',P'-diethylester from the corresponding P,P-dimethyl P',P'-diethyl ester

[[(4-Chlorophenyl)thio]methylidene]bisphosphonic acid P,P-diisopropylester from the corresponding tetraisopropyl ester (31-P NMR 10.84/21.38ppm, J=15.2 Hz; D₂ O).

[[(6-Methyl-2-pyridinyl)amino]methylidene]bisphosphonic acid P,P-diethylester from the corresponding tetraethyl ester (31-P NMR 11.34/22.79 ppm,J=34.3 Hz; D₂ O).

[[(4-Methyl-2-pyridinyl)amino]methylidene]bisphosphonic acid P,P-diethylester from the corresponding tetraethyl ester (31-P NMR 11.43/22.83 ppm,J=35.0 Hz; D₂ O).

[2-(3-Pyridinyl)ethylidene]bisphosphonic acid P,P-diethyl ester from thecorresponding tetraethyl ester.

(3-Pyridinylamino)methylidene]bisphosphonic acid P,P-diethyl ester fromthe corresponding tetraethyl ester.

Example 2 Preparation of[[(4-Chlorophenyl)thio]methylidene)-bisphosphonic Acid MonoisopropylEster and its Trisodium Salt

The tetraisopropyl ester of[[(4-chlorophenyl)thio]methylidene]bisphosphonic acid (0.02 moles) wasdissolved in dichloromethane, and to' the solution was slowly added atroom temperature bromotrimethylsilane (0.062 moles). The solution wasstirred at room temperature for 3 hours, whereafter the solvent wasevaporated at reduced pressure.

The evaporation residue was dissolved in a small amount of water and thesolution was made alkaline with a dilute sodium hydroxide solution. Theproduct was precipitated by adding ethanol (31-P NMR 12.21/18.25 ppm,J=9.8 Hz; D₂ O).

Example 3 Preparation of [[(2-Pyridyl)thio]methylidene]bisphosphonicAcid Triisopropyl Ester and its Sodium Salt

[[(2-Pyridyl)thio]methylidene]bisphosphonic acid tetraisopropyl ester(0.02 moles) was dissolved in acetonitrile, and to the solutionchloro(tert-butyl)(dimethyl)silane (0.022 moles) dissolved inacetonitrile was slowly added. The solution was stirred for 4 hours at60° C. The solvent was evaporated and the evaporation residue wasdissolved in a small amount of water. The solution was made alkalinewith a dilute sodium hydroxide solution and the product precipitated byadding ethanol (31-P NMR 7.78/23.76 ppm, J=9.6 Hz; D₂ O).

In a corresponding manner the following compounds using in the place ofchloro(tert-butyl)(dimethyl)silane for example bromotrimethylsilane (1equivalent) may be prepared:

[2-(2-Pyridinyl)ethylidene]bisphosphonic acid trimethyl ester from thecorresponding tetramethyl ester.

[2-(3-Pyridinyl)ethylidene]bisphosphonic acid triethyl ester from thecorresponding tetraethyl ester.

[[(3-Pyridinyl)thio]methylidene]bisphosphonic acid triethyl ester fromthe corresponding tetraethyl ester.

[[(2-Pyridinyl)thio]methylidene]bisphosphonic acid dimethyl isopropylester from the corresponding isopropyl trimethyl ester.

[2-(3-pyridinyl)ethylidene]bisphosphonic acid triisopropyl ester (31-PNMR 26.23/15.09 ppm; CDCl₃) .

[[(4-Methyl-2-pyridinyl)amino]methylidene]bisphosphonic acid triethylester from the corresponding tetraethyl ester (31-P NMR 8.62/26.15 ppm,J=25.4 Hz; D₂ O).

[1-Hydroxy-2-(3-pyridinyl)ethylidene]bisphosphonic acid triisopropylester from the corresponding tetraisopropyl ester.

Example 4 Preparation of [[(3-Methyl-2-pyridinyl)amino]methylidene)Bisphosphonic Acid P,P'-diethyl Ester

[[(3-methyl-2-pyrdinyl)amino]methylidene) bisphosphonic acid tetraethylester (0.015 moles) was dissolved in aqueous ethanol and concentratedsodium hydroxide solution (0.05 moles) was added to the solution. Thesolution was stirred over night. The solvent was evaporated and theevaporation residue stirred into ethanol. The product was filtered anddried (31-P NMR 16.60 ppm; D₂ O).

In a corresponding manner may be prepared:

[[(2-Pyridinyl)amino]methylidene]bisphosphonic acid P,P'-diethyl ester(31-P NMR 16.37 ppm; D₂ O).

[[(4-Pyridinyl)amino]methylidene]bisphosphonic acid P,P'-diethyl ester.

[[(4-chlorophenyl)thio]methylidene]bisphosphonic acid P,P'-diisopropylester from the corresponding tetraisopropyl ester (3]-P NMR 14.00 ppm;D₂ O).

[2-(2-Pyridinyl)ethylidene]bisphosphonic acid P,P'-diisopropyl esterfrom the corresponding tetraisopropyl ester.

[2-(3-Pyridinyl)ethylidene]bisphosphonic acid P,P'-diethyl ester fromthe corresponding tetraethyl ester.

[1-Hydroxy-2-(2-pyridinyl)ethylidene]bisphosphonic acid P,P'-dimethylester from the corresponding tetramethyl ester.

[1-Hydroxy-2-(3-pyridinyl)ethylidene]bisphosphonic acid P,P'-diethylester from the corresponding tetraethyl ester.

[[(2-Hydroxy-3-pyridinyl)amino]methylidene]bisphosphonic acidP,P'-diethyl ester from the corresponding tetraethyl ester.

[[(2-Methoxy-3-pyridinyl)amino]methylidene]bisphosphonic acidP,P'-diethyl ester from the corresponding tetraethyl ester.

[[(4,6-Dihydroxy-2-pyrimidyl)amino]methylidene]bisphosphonic acidP,P'-diethyl ester from the corresponding tetraethyl ester.

Example 5 Preparation of[[(6-Methyl-2-pyridinyl)amino]methylidene)bisphosphonic AcidP,P'-diethyl Ester and its Disodium Salt

The tetraethyl ester of[[(6-methyl-2-pyridinyl)amino]methylidene)bisphosphonic acid (0.009moles) was dissolved in a mixture of morpholine (40 ml) anddichloromethane (50 ml). The solution was stirred for a day. The solventwas evaporated and the morpholinium salt of the product was dissolved inacetone. To the solution a sodium hydroxide solution was added (0.02moles), whereby the product precipitated in the form of the disodiumsalt (31-P NMR 16.45 ppm; D₂ O).

In the same manner may be prepared, also using instead of morpholinee.g. piperidine, 2-methylpiperidine or 4-benzylpiperazine

[[(4-pyridinyl)amino]methylidene]bisphosphonic acid P,P'-dimethyl ester,

[[(3-pyridinyl)thio]methylidene]bisphosphonic acid P,P'-diethyl ester,.

[[(3-pyridinyl)amino]methylidene]bisphosphonic acid P,P'-dimethyl ester,

[2-(2-pyridinyl)ethylidene]bisphosphonic acid P,P'-dimethyl ester.

Example 6 Preparation of[[(4-Methyl-2-pyridinyl)amino]methylidene)bisphosphonic AcidP,P'-diethyl Ester and its Disodium Salt

The tetraethyl ester of

[[(4-methyl-2-pyridinyl)amino]methylidene)bisphosphonic acid (0.02moles) was dissolved in dichloromethane and to the solutionbromotrimethylsilane (0.042 moles) was slowly added at room temperature.The solution was stirred for 3 hours. The solvent was evaporated atreduced pressure. To the evaporation residue, a sodium hydroxidesolution (0.04 moles) was added as well as an equal volume of ethanol,whereby the product precipitated as the disodium salt (31-P NMR 16.39ppm; D₂ O).

In a corresponding manner may be prepared:

[2-(2-Pyridinyl)ethylidene]bisphosphonic acid P,P'-diisopropyl esterfrom the corresponding tetraisopropyl ester.

[[(4-Chlorophenyl)thio]methylidene)bisphosphonic acid P,P'-dimethylester from the corresponding tetramethyl ester.

[[(2-Pyridinyl)thio]methylidene]bisphosphonic acid P,P'-dimethyl esterfrom the corresponding tetramethyl ester.

[2-(2-Pyridinyl)ethylidene]bisphosphonic acid P,P'-diisopropyl esterfrom the corresponding P,P'-dimethyl P,P'-diisopropyl ester.

[[(3-Pyridinyl)thio]methylidene]bisphosphonic acid P,P'-dimethyl esterfrom the corresponding tetramethyl ester.

[2-(3-Pyridinyl)ethylidene]bisphosphonic acid P,P'-diisopropyl esterfrom the corresponding P,P'-dimethyl P,P'-diisopropyl ester.

[1-Hydroxy-2-(3-pyridinyl)ethylidene]bisphosphonic acid P,P'-diisopropylester from the corresponding tetraisopropyl ester.

Example 7 Preparation of[[(6-Methyl-2-pyridinyl)amino]methylidene)bisphosphonic Acid MonoethylEster and its Trisodium Salt

[[(6-methyl-2-pyridinyl)amino]methylidene)bisphosphonic acidP,P'-diethyl ester prepared according to the Example 4 (0.01 moles) wasslurried in a 15% hydrochloric acid solution and the solution wasstirred at 80° C. The progress of the reaction was followed with ³¹ PNMR. After the reaction had ceased the mixture was evaporated todryness, the evaporation residue dissolved in a sodium hydroxidesolution and the trisodium salt formed precipitated by adding ethanol.The product was filtered and dried (yield 60%, 31-P NMR 11.73/19.11 ppm;J=24.7 Hz; D₂ O).

In a corresponding manner may be prepared:

[1-Hydroxy-2-(2-pyridinyl)ethylidene]bisphosphonic acid monoisopropylester from the corresponding P,P'-diisopropyl ester.

[2-(3-pyridinyl)ethylidene]bisphosphonic acid monoisopropyl ester (31-PNMR 18.76/17.45 ppm; CDCl₃).

[[(2-Pyridinyl)thio]methylidene]bisphosphonic acid monoisopropyl esterfrom the corresponding P,P'-diisopropyl ester (31-P NMR 11.79/18.05 ppm,J=9.6 Hz; D₂ O).

[1-Hydroxy-2-(3-pyridinyl)ethylidene]bisphosphonic acid monoisopropylester from the corresponding P,P'-diisopropyl ester.

[[(3-Pyridinyl)thio]methylidene]bisphosphonic acid monoisopropyl esterfrom the corresponding P,P'-diisopropyl ester (31-P NMR 11.79/18.05 ppm,J=9.6 Hz; D₂ O).

[[(4-Methyl-2-pyridinyl)amino]methylidene]bisphosphonic acid monomethylester.

[[(3-Methyl-2-pyridinyl)amino]methylidene]bisphosphonic acid monomethylester.

[2-(2-Pyridinyl)ethylidene]bisphosphonic acid monoisopropyl ester.

Example 8 Preparation of [[(2-Pyridyl)thio]methylidene]bisphosphonicAcid P,P'-diisopropyl Ester

[[(2-pyridyl)thio]methylidene]bisphosphonic acid tetraisopropyl ester(0.01 moles) was dissolved in acetone, and to the solution sodium iodide(0.023 moles) was added. The solution was stirred at room temperaturefor 8 hours, whereafter it was filtered. The solvent was evaporated. Theproduct was isolated from the evaporation residue as the disodium saltin a manner described in the previous examples (yield 59%, 31-P NMR14.09 ppm; D₂ O).

In the corresponding manner may be prepared:

[[(2-Pyridyl)amino]methylidene]bisphosphonic acid P,P'-dimethyl esterfrom the corresponding tetramethyl ester (31-P NMR).

[[2-(3-Pyridinyl)thio]methylidene]bisphosphonic acid P,P'-diisopropylester from the corresponding tetraisopropyl ester.

[1-Hydroxy-2-(3-pyridinyl)ethylidene]bisphosphonic acid P,P'-diethylester from the corresponding tetraethyl ester.

[[2-(4-Pyridinyl)thio]methylidene]bisphosphonic acid P,P'-diisopropylester from the corresponding tetraisopropyl ester.

[1-Hydroxy-2-(2-pyridinyl)ethylidene]bisphosphonic acid P,P'-diethylester from the corresponding tetraethyl ester.

Example 9 Preparation of[Hydroxy-2-(3-pyridinyl)ethylidene]bisphosphonic Acid Monomethyl Ester

Finely ground [1-hydroxy-2-(3-pyridinyl)ethylidene]bisphosphonic acid(0.005 moles) was slurried into 100 ml of chloroform and to the mixture25 ml of an appr. 2% ether solution of diazomethane was added at roomtemperature. After the addition, mixing was continued for 1 hour. Themixture was evaporated under reduced pressure (yield 38%).

Example 10 Preparation of [[(2-Pyridinyl)thio]methylidene]bisphosphonicAcid Monoisopropyl Ester and its Trisodium Salt

[[(2-pyridinyl)thio]methylidene]bisphosphonic acid tetraisopropyl ester(0.01 moles) was dissolved in toluene and to the solution methanesulphonic acid (0.06 moles) was added. The solution was stirred whileheating and the progress of hydrolysis was followed with 31-P NMR. Themixture was cooled and the solvent evaporated under reduced pressure.The evaporation residue was dissolved in a dilute sodium hydroxidesolution and the product was precipitated by adding acetone (yield 62%,31-P NMR 11.79/18.05 ppm, J=9.6 Hz; D₂ O).

In the same manner may be prepared:

[2-(3-Pyridinyl)-1-hydroxyethylidene]bisphosphonic acid P,P'-diisopropylester from the corresponding tetraisopropyl ester.

[2-(3-Pyridinyl)-t-hydroxyethylidene]bisphosphonic acid monomethyl esterfrom the corresponding tetramethyl ester.

[2-(2-Pyridinyl)-1-hydroxyethylidene]bisphosphonic acid P,P'-diisopropylester from the corresponding tetraisopropyl ester.

[2-(3-Pyridinyl)ethylidene]bisphosphonic acid P,P-diisopropyl ester fromthe corresponding tetraisopropyl ester.

Example 11 Preparation of[[(4-Chlorophenyl)thio]methylidene]bisphosphonic Acid P,P'-dimethylEster and its Disodium Salt

A mixture of [[(4-chlorophenyl)thio]methylidene]bisphosphonic acidP,P'-dimethyl P,P'-bis(trimethylsilyl) ester (0.01 moles) and dilutehydrochloric acid was stirred at 0° C. for 0.5 hours. To' the filteredsolution' dilute sodium hydroxide was added (0.01 moles excess) and theproduct precipitated with ethanol.

In a corresponding manner may be prepared

[2-(2-Pyridinyl)ethylidene]bisphosphonic acid monoethyl ester

[2-(3-Pyridinyl)ethylidene]bisphosphonic acid monomethyl ester

[[(4-chlorophenyl)thio]methylidene]bisphosphonic acid monoethyl ester.

We claim:
 1. Bisphosphonic acid derivatives having the formula I##STR12## in which formula R¹, R², R³ and R⁴ independently are astraight or branched, optionally unsaturated C₁ -C₇ -alkyl or C₂ -C₇-alkenyl or hydrogen, whereby in the formula I at least one of thegroups R¹, R², R³ and R⁴ is hydrogen and at least one of the groups R¹,R², R³ and R⁴ is different from hydrogen,Q¹ is hydrogen or hydroxyl, Q²is the group

    Y--X--(CH.sub.2).sub.n --

wherein Y is phenyl, pyridinyl, piperidinyl or pyrimidinyl which isunsubstituted or substituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy, halogen,hydroalkyl or nitro, X is S or NH, and n=0, or X is a direct bond andn=1, provided that as a ring atom of the ring Y and/or a chain atom ofthe group X, there is always at least one heteroatom from the group of Nand S, including the stereoisomers, or a pharmacologically acceptablesalt thereof.
 2. Mono- or dimethyl, mono- or diethyl, mono- ordiisopropyl esters of the formula I according to the claim 1, wherein Q¹is hydrogen and Y is unsubstituted or methyl-substituted pyridine orpiperidine, n is 0 and X is NH, or S.
 3. Compound of the formula Iaccording to the claim 1, whichis[[(6-methyl-2-pyridinyl)amino]methylidene]bisphosphonic acidP,P'-diethyl ester, [[(2-pyridinyl)amino]methylidene]bisphosphonic acidP,P'-diethyl ester, [[(2-pyridinyl)amino]methylidene]bisphosphonic acidP,P-dimethyl ester,[[(3-methyl-2-pyridinyl)amino]methylidene]bisphosphonic acidP,P'-diethyl ester,[[(4-methyl-2-pyridinyl)amino]methylidene]bisphosphonic acidP,P'-diethyl ester, [[(2-pyridinyl)thio]methylidene]bisphosphonic acidmonoisopropyl ester, [[(4-chlorophenyl)thio]methylidene]bisphosphonicacid P,P'-dimethyl and monoetyl ester,[[(6-methyl-2-pyridinyl)amino]methylidene]bisphosphonic acid monoethylester, [[(3-methyl-2-pyridinyl)amino]methylidene]bisphosphonic acidmonomethyl ester, [[1-hydroxy-2-(3-pyridinyl)]ethylidene]bisphosphonicacid monoisopropyl ester,[[1-hydroxy-2-(3-pyridinyl)]ethylidene]bisphosphonic acid monomethylester, [2-(2-pyridinyl)ethylidene]bisphosphonic acid monoisopropylester, [2-(3-pyridinyl)ethylidene]bisphosphonic acid monomethyl ester,[[(3-pyridinyl)amino]methylidene]bisphosphonic acid P,P'-dimethyl ester,[[(3-pyridinyl)thio]methylidene]bisphosphonic acid P,P'-diethyl ester,[[(4-pyridinyl)thio]methylidene]bisphosphonic acid P,P'-diethyl ester,[[(3-pyridinyl)thio]methylidene]bisphosphonic acid monoisopropyl ester.4. Pharmaceutical composition for the treatment of disorders relating tothe metabolism of calcium and other bivalent metals and thepyrophosphate functions of the body, characterized in that it containsas the active agent a compound having the formula I according toclaim
 1. 5. A method of treating a physiological disorder byadministering to a patient a pharmacological composition for thetreatment of disorders relating to the metabolism of calcium and otherbivalent metals and the pyrophosphate functions of the body,characterized in that it has as an active agent a compound having theformula I according to claim 1.